In many industries and applications there has been a shift away from printing documents including transaction documents (e.g., receipts, tickets, gift certificates, sweepstakes and the like) using bond paper, toward printing such documents using thermal paper or media in direct thermal printers. In direct thermal printing, a thermal print head selectively applies heat to thermal paper or other sheet media, which includes a substrate with one or more thermally sensitive coatings that change color when heat is applied, thereby providing “printing” on the coated substrate.
Direct thermal printing includes single-sided direct thermal printing for thermal printing of one side of the thermal media, and dual-sided direct thermal printing for thermal printing of both sides of the thermal media. In dual-sided direct thermal printing, a thermal printer is configured to allow concurrent printing on both sides of thermal media moving along a feed path through the thermal printer as further described in U.S. Pat. Nos. 6,784,906 and 6,759,366. In such a dual-sided direct thermal printer, a thermal print head is disposed on each side of two-sided thermal media comprising, inter alia, a substrate with a thermally sensitive coating on each of two opposing surfaces thereof. Each thermal print head faces an opposing platen across the thermal media from the respective print head. During printing, the opposing thermal print heads selectively apply heat to opposing sides of the two-sided thermal media, such that printing is provided on both sides thereof.
Single or dual-sided direct thermal printing is typically provided in one color (e.g., black, blue or red) on one or both imageable sides of respective single or dual-sided direct thermal media. For dual-sided direct thermal printing, a different color (e.g., black, red or blue) may be provided on each of two opposite media sides. However, printing of one side of a document in one color (e.g., black, blue or red), such as for printing of transaction detail, and simultaneously printing of the other side of the document in full color (e.g., CMYK), such as for printing of an advertisement or a coupon, which may be advantageous for point-of-sale applications, among others, is not readily available. Although single-sided direct thermal color printing has been developed and dual-sided direct thermal color printing is under development, they remain prohibitively expensive for many applications, especially in printing transaction documents containing multi-color images such as advertising at the point of sale. However, color inkjet printing is less expensive and has been employed in a variety of single-sided full color applications, such as desktop printing, for some time.